A significant factor in property insurance liability is the replacement cost of roofs and roofing materials, especially in areas prone to severe weather. Accordingly, it may be desirable for insurance companies to offer insurance policies that cover the actual cash value (ACV) of a roof, rather than the replacement cost of the roof. ACV takes into account the depreciation in roof value that occurs naturally over the lifespan of the roof. For example, the ACV of a roof may be equal to the replacement cost of the roof multiplied by the percentage of useful remaining life of the roof. In order to accurately calculate the ACV, knowledge of the age of the roof is important.
For newer buildings, the age of the roof may correlate to the date on which the building was erected. This correlation, however, may not apply to older buildings because roofs are replaced periodically (e.g., every 20-50 years) due to ordinary wear and tear. In regions prone to severe weather, roofs may be replaced at more frequent intervals due to, for example, damage caused by wind and hail. Because a number of variables affect the timing of roof replacement, it is generally not possible to estimate roof age solely based on the date the building was erected.
One conventional method for determining roof age involves having an appraiser or inspector climb onto the roof and perform a visual inspection. This method exposes the inspector to the risk of falling, especially if the roof is icy or wet. In addition, this method can be costly and time-consuming as it requires an inspector with specialized training and, in some cases, requires an inspector to travel significant distances to reach the site of the building. Additionally, assessments by inspectors are inherently subjective and can lead to inconsistent and unreliable results. For instance, different lighting conditions and shingle types can make it difficult, even for an experienced inspector, to accurately assess the age of the roof.
In some cases, it is possible to assess roof age by referencing a public record of construction permits issued for roof replacement or repair. However, this method is not effective in jurisdictions which do not require a permit for roof repair or replacement. Furthermore, even if a permit is required, some building owners may skip the step of obtaining a permit, particularly if they plan to replace the roof themselves without the assistance of a professional construction company.
Until recently, satellite imagery was not considered a feasible option for determining roof age because of the substantial expense associated with traditional satellites, and because of the rather infrequent intervals with which traditional satellite systems can image a particular geographic location. Some older satellite systems, for example, may have the ability to image a particular geographic location only once a month. This aspect of older satellite systems, in combination with their significant cost, tends to make them an economically unattractive option for frequently monitoring a roof of a building or multiple building roofs.